Separation means



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SEPARATION NUEANS Continuation of application Ser. No. 594,241, May 17, 15251.08 This application Oct. 18, 1945, Ser. No.

Claims. (Cl. 102- 49) The invention described herein may be manufactured and used by or for the Government, for governmental purposes, without the payment to me of any royalty thereon.

This invention relates, generally, to rockets adapted to drive shells into muzzle loading guns, and it has particular relation to means for attaching rockets to such shells.

This application is a continuation of my previous application, Serial No. 594,241, filed May 17, 1945, now Patent No. 2,519,905 and assigned to the assignee of the present application.

In muzzle-loaded ordnance, such as the 4.2 Chemical Mortar (pages 372 through 378, Chemicals in War by Prentiss, 1937, McGraw-Hill Book Co., Inc.) the force of gravity is used to move the loaded projectile or shell from the muzzle, down the mortar tube or barrel, and into the firing position. A fixed firing pin at the tube cap end or base of the mortar, fires the propellant as soon as the projectile slides back into the firing position there against. This method of loading and firing is satisfactory for high-angle fire, but is impossible for lowangle fire because of insufficient gravitational force to move the projectile into the firing position. That is, the mortar barrel must be elevated to at least a certain minimum angle in order for it to be thus operated.

I have carried out considerable research and development with a particular view of making the 4.2 Chemical Mortar a more effective and versatile weapon. One phase of this development has been the provision of a recoilless 4.2 Chemical Mortar which avoids the necessity for the heavy baseplate previously required. My invent'ions pertaining to the recoilless mortar are covered in my previous application, Serial No. 589,500 filed April 21, 1945, now Patent No. 2,598,256 and assigned to the assignee of the present application.

However, even with the improved recoilless 4.2 Chemical Mortar, the limitations of high-angle fire still existed. In my previously mentioned Patent No. 2,519,905 several embodiments of an invention are described whereby it is possible to fire the 4.2 Chemical Mortar not only at low angles of elevation, but even with the mortar barrel in a depressed position. Briefly stated, this previous invention to which, Patent No. 2,519,905 is directed, resides in providing drive rockets or rocket type motors which can be attached to the nose end of a mortar shell, and which will develop sufiicient driving force to drive the shell backward through the barrel into the firing position.

The driver rockets described in my previous Patent No. 2,519,905, functioned very satisfactorily in the matter intended, except in one respect. That is, the means for permitting detachment of the used rocket motor or driver from the nose end of a shell after it left the mortar barrel, although practical and operative, was not entirely satisfactory in certain respects.

Accordingly, the object of the present invention, generally stated, is to provide improved means for attaching driver to the nose ends of mortar shells which will perice mit the driver rockets to be separated from the mortar shells when fired.

More particularly, the object of my present invention is to provide means for attaching driver rockets to the nose ends of mortar shells, which will permit the driver rockets to be separated from the mortar shells when fired, which means is extremely simple, economical to manufacture, and provides maximum dependability in use.

Briefly stated, the present invention resides in using a sleeve to connect the driver rockets to the mortar shells, having the sleeve provided with a plurality of slots so as to separate the sleeve into two parting sections interconnected at a plurality of integral sections. The combined strength of the integral sections is such as to provide adequate handling strength and sufiicient strength to withstand the driving force of the rocket, but of insufiicient strength to withstand the set back force when the mortar shell leaves the mortar barrel.

For a more complete understanding of the nature and v scope of my present invention, reference may be had to the following detailed description taken with the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional view of a driver rocket with a slotted sleeve attaching end forming one embodiment of this invention:

Fig. 2 is a sectional View taken on line 2-2 of Fig. 1 and illustrating the manner in which the slots may be formed in the sleeve attaching end;

Fig. 3 is a fragmentary elevational view of a modified rocket attaching sleeve wherein the slots are slanted;

Fig. 4 is an enlarged longitudinal vertical sectional view of the attaching sleeve of Fig. 3; and

Fig. 5 is a side elevational view of a modified safety pin.

Referring to Fig. 1 of the drawings, a driver rocket is shown having a slotted sleeve attaching end 6 and motor housing 7. The sleeve 6 and the housing 7 are integrally formed with a counterbored wall 8 therebetween. The housing 7 contains a cylindrical powder stick or grain 9 which is retained in place therein by an end plug 10 having a plurality of integral fins 11 extending from its inner face so as to form a powder trap. The plug is provided with a venturi-shaped opening 12 which is normally closed with a stopper 13. The powder grain 9 may be formed of Russian powder, H-4 (T-2) powder, or other suitable rocket powder.

The firing and ignition means of the driver rocket 5 are carried in a tube 14 having an inwardly directed flange 15 formed on the end which may be screwed or silver soldered within the wall 8, as shown. The tube 14 is internally threaded at its right end so as to carry a blank cartridge or percussion cap 16 between a centrally bored plug 17 and a cap 118. The rim or flange 20 of the cartridge 16 is held between the plug 17 and the cap '18 as shown. The cap 18 is provided with a number of circumferentially located vents 21 through which the blast from the cartridge 16 may be conducted to ignite an igniter tube or sleeve 22. The igniter tube '22 in turn serves to positively ignite the powder stick 9.

Unless the vent holes 21 are sufiiciently large, there may be sufficient pressure built up in the cap 18 to break it open. If this occurred, the broken section might lodge in and plug the orifice 12. Accordingly, if deemed desirable in any case, the end of the cap 18 may be cut off flush with the end of the cartridge 16. This modification would simplify the construction and insure against a blow-up. In any case, there will be no difficulty in igniting the igniter 22.

The striker mechanism for setting off the cartridge 16 comprises a firing pin 23 having a striker end 24. The firing pin 23 is actuated by a coil spring 25 held between a washer 26 carried on the striker end of the firing pin 23 and the outwardly turned flange 27 of a spring compressing member 28. The sleeve portion of the member 28 fits'slidably through the smaller section of the opening through the wall or partition 8. On its outer or free end the member 28 carries a washer 30 which is secured thereto by a number of turned over prongs 3 1 bent back through accommodating openings in the Washer 30 as shown.

The firing pin 23 is normally retained in the retracted safety position shown, by means of a safety pin 32 which extends through the head 33 formed on the left end of the firing pin 23. The safety pin 32 extends diametrically through opposite sides of the sleeve attaching end 6. The member 28 is provided with diametrically opposing longitudinal slots 34- to accommodate the safety pin 32.

It will be noted that no positive provision is made for securing the safety pin 32 in place prior to its withdrawal other than friction. Since the spring tension of spring 25 is relatively low in the unarmed position, there is a possibility that the pin 32 may be prematurely removed. This might result in firing the rocket prematurely, or at least in making it necessary to reassemble the components. This condition can be readily remedied by making the pin 32 of rectangular cross section and providing it with notches for engaging the sides of the slots 34. The head 33 would then be provided with a rectangular hole for receiving the safety pin. Referring to Fig. 5 of drawing, a modified safety pin 60 is shown having a square or rectangular cross section. The pin 60 is provided with slots or notches 61. The pin 60 is inserted in the head 33 so that the spring 25 forces the notches 61 against the ends of the slots 34 thereby making it impos sible to withdraw the pin. During arming of the rocket 5, the ends of the slots 34 disengage with the notches 61, thereby permitting its withdrawal. However, when the rocket 5 is armed, the spring 25 will be under considerable compression, so that the friction will require a definite withdrawing force to be exerted in order to remove the pin 60, thereby preventing its accidental withdrawal.

The attaching end 60f the driver rocket is internally threaded to permit the driver rocket 5 to be screwed onto the nose of a mortar shell (not shown). As the driver rocket 5 is thus screwed onto the nose of a mortar shell, the nose engages the washer 30 so as to move the spring compressing member 28 inwardly, thereby compressing the spring 25.

In order to permit the driver rocket 5 to separate from the mortar shell to which it is attached when the shell leaves the mortar barrel, the sleeve attaching end 6 is slotted as shown. There are two pairs of slots 35-35 and 36-36. The slots may be cut in the sleeve end by two pairs of opposing mill wheels or cutters 4040 and 41-41 as shown in Fig. 2. Each of the slots so formed has an arcuate length of approximately 90 with the'two pairs of slots 35-35 and 36-36 lying respectively, in parallel planes extending at right angles to the longitudinal axis of the rocket motor 5. As will be seen, the slots 3535 and '3636 divide the sleeve end 6 into two sections integrally interconnected at four points 42 between the ends of the slots- In order to obtain the best conditions, the radius of the cutters should be equal to the mean radius of the sleeve. In operation, a driver rocket is screwed onto the nose end of a mortar shell thereby compressing the spring 25 and arming the igniter mechanism. The shell is then placed part way into the mortar muzzle and when ready to be fired, the pin 32 is withdrawn thereby permitting the spring 25 to drive the firing pin head 24 against the percussion cap 16 so as to detonate it. The cap in turn causes the ignition of the powder stick 9 and the driver rocket forces the shell into the mortar barrel until it reaches the firing pin and the propellent charge carried at the base of the shell is thereby ignited.

The combined strength of the'four slot connecting, sections 42 is such that it is overcome by the set back force the propellent charge imparts to the shell. Accordingly, as the shell leaves the muzzle in its flight the sleeve 6 will have failed or sheared at the sections 42, permitting the driver rocket to fall away.

The following design figures for the driver rocket are given by way of illustration: Over-all length, 3.75". Mean diameter of coil spring 25, 0.25", diameter of wire, 0.54", inside diameter, .196", outside diameter .304", number of active turns 13, and total number of turns, 15. Inside diameter of tube '14, outside diameter, /2". Inside diameter of powder stick 9, /s", outside diameter 1', and length 1 /2". Inside diameter of motorhousing 7, 1%", outside diameter 1%. Firing pin 23 diameter Diameter of enlarged head 33, 7 Diameter of withdraw pin 32, 7 Firing pin travel Spring tension in unarmed position, 5 lbs. Deflection in the unarmed position, /8 Spring tension in the armed position, 20 lbs. Inch pound of work, 4.2. Width of slots 35--35 and 3fi-36, Width of slot interconnecting sections 42,

Upon trial, it was found that the form of slot arrangement provided for in the end 6 of the driver rocket 5 sometimes failed to permit parting. Shearing of the sections 42 took place as intended, but there was an interlocking action after shear which prevented parting. Accordingly, a modified form of slot arrangement was worked out which has proven to be entirely satisfactory and dependable. This arrangement is shown in connection with Figs. 3 and 4 of the drawings.

Referring to Figs. 3 and 4, the attaching end' of a driver rocket is shown, generally, at 50 in the form of a cylindrical sleeve 51 having three canted slots 52 cut therein. The slots are somewhat longer than 120 in circulate length (due to the canted arrangement) with the three left ends 53 of the slots 52 lying'in a plane perpendicular to the longitudinal axis of the sleeve 51, and the three right ends 54 likewise lying in a plane perpendicular to the axis. Three interconnecting sections 55 are left between the ends of the slots 52. In the case of the three-slot design, the radius of the cutter wheels should be about 1.4 times the mean radius of the attachment sleeve. The sections 55 shear as the attached mortar shell is fired from the mortar barrel. The slanted arrangement given the slots 52 make it impossible for interlocking of the sleeve sections after shearing of the sections 55. I

In order to obtain maximum advantage of the canted slot arrangement when a driver rocket is used in connection with a mortar shell which rotates during its trajectory, the slots should be so arranged that the" inclines on the portion of the attachment sleeve remaining on the nose of a shell, tend to push the rocket section forward. If the inclines were arranged in the reverse direction in such a case, there would be a tendency for the sheared sections to remain together, even though the interconnecting sections were completely severed.

Obviously, the number of canted slots could he greater than three and could be reduced to one. However, one or two slots would not ordinarily give enough rigidity, While more than three appears to be unnecessary. Accordingly, the three-slot arrangement shownin Figs. 3 and 4, is the presently preferred construction.

Since certain further changes may be made in the foregonig. constructions and different embodiments of the invention may be made, it is intended that the foregoing description and discussion of the invention, be interpreted' as illustrative and not ina limiting sense.

I claim: 7

1. Means for securing a rockettype' driver to the nose end of a muzzle loaded type mortor shell adapted to be propelled by a propellent charge, said means comprising a sleeve with a. plurality of slots providedtherein and extending therearound, said slots having a combined length; at least percentof the length of the periphery of said sleeve, and said slots separating said sleeve into two sections having integrally interconnecting portions at the ends of said slots by the sleeve material therebe/ tween, said interconnecting portions of said two sleeve sections having a sufiicient mechanical strength to withstand the driving force of the rocket type driver but insutficient strength to withstand the set back force delivered by the propellent charge for the motor shell, whereby said integral interconnection fails as the mortar shell attached thereto leaves a mortar barrel so as to permit the rocket type driver to become separated from the mortar shell.

2. The means of claim 1 wherein an end of each slot lies in one plane perpendicular to the longitudinal axis of the sleeve and the other end of each slot lies in a second plane parallel to the first mentioned plane.

3. The means of claim 1' wherein the sleeve is cylindrical.

4. The means of claim 1 where there are three slots which are canted relative to a plane perpendicular to the longitudinal axis of said sleeve.

5. The means of claim 1 wherein the-re are four slots each having an arcuate length of about 90 wifla one pair of slots being diametrically opposed and lying in a plane perpendicular to the longitudinal axis of said sleeve which the other pair of slots are also diametrically opposed to lie in a plane parallel to said first plane.

References Cited in the file of this patent UNITED STATES PATENTS 1,614,499 Stirton Ian. 18, 1927 FOREIGN PATENTS 91,905 Switzerland Dec. 1, 1921 373,719 Germany Apr. 14, 1923 812,680 France Feb. 8, 1937 516,463 Great Britain Jan. 2, 1940 

